Fire tube boiler



Jan. 25, 1966 M. KOENIG FIRE TUBE BOILER 2 Sheets-Sheet 1 Filed Jan. 23, 1964 INVENTOR. Morris Koenig 7 ATTORNEY FIG.10

FIG. 11

Jan. 25, 1966 M. KOENIG 3,231,014

FIRE TUBE BOILER Filed Jan. 23, 1964 2 Sheets-Sheet 2 INVENTOR. Morris Koenig naw ATTORNEY United States Patent This invention relates in general to a fire tube boiler are, and more specifically to a coating and/or a liner construction for use in the fire tubes of a fire tube boiler for protecting the boiler tubes from the corrosive and erosive constituents of the hot products of combustion flowing therethrough.

Considerable difficulty has heretofore been encountered in prohibiting the corrosive and erosive effects which the products of combustion have on the internal surfaces of the fire tubes in a fire tube boiler. Heretofore, considerable effort and the expenditure of huge sums of money have been made in an effort to develop alloys with the needed properties to resist corrosion and the like. However, such eiforts have yet to be proved successful. Also, troublesome in the operation of fire tube boilers is the excessive build up of high temperature deposits which accumulate in the fire tubes of such boilers. The build up of such deposits results in a reduction of the overall efficiency of such boilers. This is so because once the deposits have been initiated, a substantial change may occur in the character of a boundary layer, and if the deposit becomes thick enough in the character of the aerodynamic behavior of the gases passing nearby. As a result, this can lead to an acceleration or aggravation in the growth of such deposits in the tubes.

Further, these deposits substantially increase the cost of maintenance. This is because frequent cleaning of the tubes is required to maintain the boiler at optimum operating efficiency. Because the cleaning operation of the fire tubes constitutes a tedious, disagreeable and time consuming task, it is many times intentionally overlooked by the maintenance personnel, or at best, is only partially performed. For this reason, actual experience has shown that such boilers are usually operated at substantially less than their optimum rated efficiency.

An object of this invention is to overcome the above noted disadvantages by providing a readily removable and expandable liner for protecting the tubes of a fire tube boiler from excessive erosion and corrosion.

Another object of this invention is to protect the fire tube proper of a fire tube boiler by directly coating the inner surfaces of such tubes with a high heat resistant material.

Another object is to provide a liner constructed and arranged so that it can be readily inserted and removed from the fire tube with a minimum of effort and a maximum of ease.

Another object is to provide a liner for a fire tube boiler which is coated with a high temperature substance so as to enhance the heat transfer therethrough and to resist the erosive and/ or corrosive effects of the products of combustion thereon.

Another object is to provide a liner formed of suitable sheet material rolled to define a tube which can be readily expanded or contracted to accommodate a wide range of fire tube sizes.

Still another object is to provide a fire tube liner with expanded surface area to enhance the heat transfer therethrough.

In accordance with this invention, the foregoing objects, and other features and advantages are readily attained by coating the internal surface of a fire tube boiler directly with a high temperature heat resistance material. In another form of the invention the foregoing objects and advantages are attained, by providing 3,231,914 Patented Jan. 25, I966 each of the fire tubes of a fire tube boiler with a liner constructed and arranged so as to be rendered readily removable and disposable after use. The liner may be formed of any suitable base material which can be rolled to define a tube, which is sized so that it can be readily inserted into the bore of a fire tube of a fire tube boiler. In one form of the invention, the longitudinal ends of the material from which the liner tube is rolled are disposed in overlapping relationship with respect to each other to define a readily expandable split tube or liner arrangement, the outside diameter of which is rendered readily adjustable whereby it can be readily inserted into the tube; and when in place, the inherent resiliency or elasticity of the rolled liner tube is such that it will expand to frictionally engage the interior walls of the fire tube. To enhance the heat transfer through the walls of the liner and to the walls of the fire tube and for enhancing the flow of the products of combustion, through the bore of the liner, the surfaces of the liner in another form of the invention are coated with a high temperature material. Such coating materials may comprise a graphite silicate composition, a porcelain-enamel composition, a glass frit composition or any other suitable high temperature coating composition. If desired, the surfaces of the liner may be expanded by means of dimples, flutes, lands or groove-s to provide further means for enhancing the distribution of heat therethrough and also to effect a mechanical bond for the coating of material placed thereon. Also, the expanded means may be also utilized as complemental interlocking means to secure the ends of the roller tube in a predetermined overlapping position. In another form of the invention, the free edges of the rolled tube may be provided with complemental interlocking means to define a seam for positively maintaining the tube in its rolled position. As another form, the liner may be formed of open mesh material roller to define a tubular structure which is then rendered imperforate by coating the open mesh material with a layer of high temperature material, as for example, porcelain-enamel or a graphite silicate composition or the like.

A feature of this invention resides in the provision that the coating and/or liner constructed and arranged in accordance with this invention is relatively simple to fabricate, relatively inexpensive to make, and is positive in operation.

Another feature of this invention resides in the provision that the liner and outer surfaces of the liner are coated with a layer of high temperature material to enhance the heat transfer and to minimize the corrosive and erosive effects of the products of combustion flowing therethrough on the tubes.

Another feature of this invention resides in the provision that the liner is provided with an expanded surface area to enhance the heat transfer therethrough.

Another feature of this invention resides in the provision that the liner may be formed of open mesh material coated with a high temperature material so as to render the tube so formed imperforate.

Another feature resides in the provision wherein the fire tubes can be protected by applying a coating of high temperature resistant material directly to the internal walls thereof.

Other features and advantages will become more readily apparent when considered in view of the drawings and specifications in which,

FIGURE 1 is a partial front end view of the tube sheet of a fire tube boiler in which the fire tubes are each provided with a liner in accordance with this invention.

FIGURE 2 illustrates a fire tube and liner construction therefrom with portions thereof shown in section, the section thereof being taken along line 2-2 of FIG. 3-

FIGURE 3 is a cross sectional view taken through the fire tube and liner along line 3-3 of FIG. 2.

FIGURE 4 is a sectional view similar to that of FIG. 3 but illustrating a slightly modified form of the invention.

FIGURE 5 illustrates another modified form of the lirier in accordance with this invention.

FIGURE 5A is a sectional view taken along line 5A- 5A of FIG. 5

FIGURES 6 to 9, respectively, are each directed to slightly modified liner constructions in accordance with this invention.

FIGURE 10 illustrates another modification of the invention.

FIGURE 11 is still another form of the invention.

Referring to FIG. 1, there is shown a fragmentary portion of the tube sheet of a fire tube boiler into which the fire tubes 21 of the boiler are rolled, expanded, or otherwise secured into the tube seats or openings 22 of the tube sheet 20. In accordance with this invention, a readily removable and disposable liner 23 is specifically constructed and arranged so as to be disposed within the bore of the fire tubes to protect the fire tubes proper from the erosive and corrosive efiects of the products of combustion.

In the form of the invention shown in FIGS. 1 to 3, the liner 23 comprises a tubular member which is rolled from a blank of suitable sheet material, as for example, mild steel and the like. referably, the thickness of the sheet material from which the liner is formed may be from O to 50 gauge. As seen, the liner 23 is rolled so that the longitudinal edge portions 23A, 23B of the blank from which the liner is formed are disposed in overlapping relationship. This construction results in a liner which is defined as a split tube with the ends disposed in overlapping position. With this construction, the outside diameter of the tube 23 can be expanded and contracted within predetermined limits, as determined by the amount of overlap. Thus the construction is such that the liner 23 so formed can be readily inserted or removed from the bore of the fire tube 21. With the construction described, it will be readily apparent that by increasing the overlap of the respective end portions, the diameter of the liner can be reduced accordingly. Consequently, by applying a force to the liner 23 so as to increase the amount of overlap to reduce the diameter, as noted, the liner 23 can be sized so that it can be readily inserted into the bore of the fire tube- Upon release of the force tending to reduce the diameter of the liner, the inherent resiliency of the rolled tube 23 will force the liner to spring outwardly so that the outer surface of the liner 23 is brought into frictional or. contacting engagement with the inner wall surface of the fire tube 21. Thus, a friction tight fit is had with the internal wall surface of its respective fire tubes.

To enhance the heat transfer between the liner 23 and its respective fire tube, a high temperature coating 24 is deposited on the exterior surface of the liner. See FIGS. 1 and 2. With the liner 2-3 in place within the fire tube, the high temperature coating 24 isdisposed in intimate contact with both the outer surface of the liner 23 and interior surface ofthe fire tube 21. A suitable high temperature coating 24 comprises a composition of 25% graphite and' 75% sodium silicate. Other suitable high temperature coatings comprising aporcelain-enamel composition, a glass frit composition, or a stainless steel powder and sodium silicate solution composition have been found suitable. Of course,other suitable highresistant coatings may also be utilized.

Inorder to minimize the tendency of solids or other, high temperature deposits to accumulate within the bore of the liner, it has also been found desirable to coat the internal surface of the liner with a layer 25 of similar high temperature material, e.g., with a graphite silicate composition. Graphite, being a natural lubricant, therefore tends to minimize or resist the solids or deposits from sticking and accumulating in the bore of the liner. The graphite silicate composition, or the like further minimizes the reaction with erosive or corrosive constituents of the products of combustion. Thus, the useful life of the liner can be extended accordingly, and the liner in turn functions to preserve the useful life of the fire tube, since the erosive or corrosive constituents of the combustion gases, as for example, the H 80 Hill and vanadium compounds are prohibited from contacting the same. As the useful life of the fire tubes proper is extended for a considerable period of time, the need and cost of replacing such fire tubes with the frequency heretofore required is greatly minimized. Also, the amount of outage time of the boiler required for tube replacement or repair is also greatly minimized. The coatings of material deposited on the surfaces of the liner 23 is such that it will deter the accumulation of soot and other solids on the internal surface of the tube, and further the removal of the soot is enhanced when soot blowers are used. Since the nature of the coating is highly alkaline, it will further function to neutralize the acidic constituents of the combustion products flowing therethrou'gh, and in this manner will deter the corrosive effects which the acidic constituents of the products of combustion would otherwise have thereon.

In another form of the invention, as shown in FIG. 4, the ends of the sheet material from which the liner 3% is formed may be provided with complementary rolled edges TWA, 3M3 arranged to mate or interlock with one another to form a seamed tube liner. In all other respects, the construction of the liner 3b of FIG. 4 and its application is similar to that described with reference to FIGS. 1 to 3.

FIGS. 5 to 9 illustrate various other modifications of a tube liner in accordance with this invention. In FIGS. 5 and 5A, the sheet material from which the tube liner is formed with a stippled or dimpled surface in which the stipples or dimples 36 project inwardly of the liner. In this manner, the surface area of the liner 35 is expanded so as to enhance the heat transfer therethrough. Also, the dimpled or stippled surface provides a means for establishing a mechanical bond for the coating of the high temperature material 37 when applied thereto. The dimples or stipples surface also may function as a mechanical grippins means for securing the overlapping ends of the liner since the inwardly extending dimples 36 formed in the outer end of the blank may be recessed in the hollow of the dimples formed on the inner end of the blank. See FIG. 5A.

The modification illustrated in FIG. 6 is similar to that of FIG. 5 with the exception that the stipples or dimples 41 formed in the surface of the liner 4t project outwardly therefrom.

In the modification of FIG. 7 a liner 45 is provided with stipples or dimples expanded surface in which the dimples 46 alternate inwardly and outwardly of the tube.

In all other respects the operations and functions of the embodiments of FIGS. 6 and 7 are similar in all respects to that of FIG. 5. Each of these forms may also be coated with. the desired high temperature material.

FIG. 8 illustrates still another modified form of the invention. In this form of the invention, the surfaces of the liner 50' are provided with longitudinally extending flutes, grooves, and lands 51 to expand the surface area thereof. These flutes or grooves 51 of FIG. 8 also function as a means of providing a mechanical bond for the layer of high temperature material which costs the same, much as the same nature as the stipples or dimples of FIGS. '5 to 7. Also the flutes adjacent the edge portions from the sheet from which the liner is rolled may aiso be utilized as a mechanical holding means for maintaining the ends of the rolled tube in a predetermined overlapped position.

The depth of the stipples or dimples of FIGS. 5 to 7, and of the flutes or grooves of FIG. 8 may range from 5 microns to 500 microns.

FIG. 9 illustrates another embodiment. In this form the lines 55 are formed of a base of wire mesh material 56 which is rolled to define a tubular structure similar to that hereinbefore described. The rolled wire or screen mesh 56 is then coated with the high temperature material 57 of the type herein described. The coating material thus seals over the openings in the wire mesh 56 to define an irnperforate tubular liner 55. In operation, it is similar to those described herein.

If desired, the fire tubes 21 may be protected from the erosive and corrosive influences of the combustion gases simply by inserting a liner 23:, as described, and free of any coating material directly into contact with the walls of the fire tubes 24 as shown in FIG. 11.

If desired in another form of the invention, FIG. 10, the coating 23A of high temperature resistant material as herein described, can be applied directly to the internal surface of the boiler tubes proper. In this form of the invention the coating material 23A will function on the boiler tube proper in substantially the same manner as it would function when used with a liner 23 as described with reference to FIG. 1.

From the foregoing, it will be readily apparent that the liners of the instant invention are relatively simple in construction and each can be easily fabricated. They each can be readily inserted into the b-ore of a fire tube with a minimum of effort and a maximum of ease. When cleaning of the fire tubes is required, the liner may be simply removed and a new clean liner installed in place thereof. In this manner cleaning of the fire tubes is effective in a simple, expedient and efiicient manner. The life of the fire tube proper is also extended over a considerable period of time. Because of the ease of cleaning afforded by the ready removal of the liner construction, the boiler may be operated at its optimum efiiciency over a greater period of time.

In accordance with this invention the high temperature coating material, as hereinbefore described, can also be utilized directly in the combustion chamber of a boiler to protect those internal combustion chamber portions, e.g., the stay bolts, welds, and the other vital portions that are vulnerable to attack by the deleterious constituents of the combustion products. It has been observed that coating the internal surfaces of a combustion chamber with the high temperature coatings, as herein described, will substantially enhance the life of such portions and the overall efficiency of the unit.

While the instant invention has been described with reference to particular embodiments thereof, it will be readily understood and appreciated that variations and modifications thereof may be readily made without departing from the spirit or scope of the invention.

What is claimed is:

1. In a fire tube boiler, a fire tube, a readily removable and disposable liner received in the bore of said fire tube for protecting the internal surfaces thereof from the corrosive and erosive constituents of the products of combustion, said liner being formed of a rolled metallic plate shaped to be received in said tube so that the exterior surface of said liner is disposed contiguous to the internal surface of said fire tube, said rolled liner having the ends of the plate defining the same disposed in overlapping position whereby the inherent elasticity of the rolled plate serves to maintain the walls of said liner in frictional engagement with said fire tube, and a high temperature coating comprised of graphite and silicate disposed on each side of said liner.

2. The invention as defined in claim 1 wherein said rolled liner is provided with a plurality of dimples formed on the surface thereof.

3. The invention as defined in claim 2 wherein said dimples project inwardly of said liner.

4. The invention as defined in claim 2 wherein said dimples project outwardly of said liner.

5. The invention as defined in claim 2 wherein said dimples project alternately inwardly and outwardly of said liner.

6. The invention as defined in claim 1 wherein said liner is provided with longitudinally extending flutes formed therein.

7. The invention as defined in claim 1 wherein the overlapping ends of the plate defining said rolled liner are provided with complementary rolled edges to interlock with one another to form a seam tube liner.

8. In a fire tube boiler, a fire tube, a readily removable and disposable liner received in the bore of said fire tube for protecting the internal surfaces thereof from the corrosive and erosive constituents of the products of combustion, said liner being formed of a rolled metallic plate shaped to be received in said tube so that the exterior surface of said liner is disposed contiguous to the internal surface of said fire tube, said rolled liner having the ends of the plate defining the same disposed in overlapping position whereby the inherent elasticity of the rolled plate serves to maintain the walls of said liner in frictional engagement with said fire tube, and a high temperature coating comprised of glass frit disposed on each side of said liner.

9. In a fire tube boiler, a fire tube, a readily removable and disposable liner received in the bore of said fire tube for protecting the internal surfaces thereof from the corrosive and erosive constituents of the products of combustion, said liner being formed of a rolled metallic plate shaped to be received in said tube so that the exterior surface of said liner is disposed contiguous to the internal surface of said fire tube, said rolled liner having the ends of the plate defining the same disposed in overlapping position whereby the inherent elasticity of the rolled plate serves to maintain the walls of said liner in frictional engagement with said fire tube, and a high temperature coating comprised of a composition of stainless steel powder and sodium silicate disposed on each side of said liner.

10. In a fire tube boiler, a fire tube, a readily removable and disposable liner received in the bore of said fire tube for protecting the internal surfaces thereof from the corrosive and erosive constituents of the products of combustion, said liner being formed of a rolled metallic plate shaped to be received in said tube so that the exterior surface of said liner is disposed contiguous to the internal surface of said fire tube, said rolled liner having the ends of the plate defining the same disposed in overlapping position whereby the inherent elasticity of the rolled plate serves to maintain the walls of said liner in frictional engagement with said fire tube, and a high temperature coating comprised of a composition of porcelain-enamel disposed on each side of said liner.

References Qited by the Examiner UNITED STATES PATENTS 459,227 9/1891 Mcllvain 138-151 948,865 2/1910 Lutz 138-146 1,237,031 8/1917 Haefiely 138-151 X 1,550,629 8/1925 Paulus 106-56 1,728,168 9/1929 Pratt 138-145 X 1,729,343 9/1929 Huas 106-56 X 1,825,678 10/1931 Pittman 138-140 1,986,561 1/1935 Davis 122-149 X 2,203,317 6/1940 Wolden 138-151 X FOREIGN PATENTS 294,687 7/ 1928 Great Britain.

ROBERT A. OLEARY, Primary Examiner.

CHARLES SUKALO, Examiner. 

1. IN A FIRE TUBE BOILER, A FIRE TUBE, A READILY REMOVABLE AND DISPOSABLE LINER RECEIVED IN THE BORE OF SAID FIRE TUBE FOR PROTECTING THE INTERNAL SURFACES THEREOF FROM THE CORROSIVE AND EROSIVE CONSTITUENTS OF THE PRODUCTS OF COMBUSTION, SAID LINEAR BEING FORMED OF A ROLLED METALLIC PLATE SHAPED TO BE RECEIVED IN SAID TUBE SO THAT THE EXTERIOR SURFACE OF SAID LINEAR IS DISPOSED CONTIGUOUS TO THE INTERNAL SURFACE OF SAID FIRE TUBE, SAID ROLLER LINEAR HAVING THE ENDS OF THE PLATE DEFINING THE SAME DISPOSED IN OVERLAPPING POSITION WHEREBY THE INHERENT ELASTICITY OF THE ROLLED PLATE SERVES TO MAINTAIN THE WALLS OF SAID LINER IN FRICTIONAL 